1. Field of the Invention
The present invention relates to drug delivery devices, and, in particular, to nebulizers used in an aerosolized drug delivery.
2. Description of the Related Art
Nebulizing drug delivery devices that use ultrasonic energy to nebulize a drug solution are generally known. Such devices typically include an acoustic wave generator to generate acoustic waves that are transmitted to a drug solution. The ultrasonic energy transmitted to the drug solution in the form of the acoustic waves energizes the drug solution such that nebulized particles of the drug solution are formed. The ultrasonic energy may be delivered with a maximum density at a focal point of the acoustic waves, and nebulization efficiency of the drug solution may be enhanced when an upper surface of a pool of the drug solution is located at or near the focal point of the acoustic waves. However, the ability to take advantage of enhanced nebulization efficiency in this manner has been limited by the fact that the upper surface of the drug solution lowers during nebulization as the amount of drug solution in the device is depleted.
It should be appreciated that several conventional nebulizing drug delivery devices are configured to deliver drug solutions to a user's lungs via inhalation. But these devices may not be capable of effectively or efficiently nebulizing various types of drug solutions for delivery that are typically delivered directly into a patient's lungs, such as through injection. Thus, typical nebulizing drug delivery devices may not be particularly effective or efficient in delivering drug solutions of a higher viscosity, and/or drug solutions that must be delivered at higher flow rates.